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Ibaraki, Japan

Tomimatsu Y.,Seiko Instruments Inc. | Tomimatsu Y.,Tukuba Research Center | Takahashi H.,Tokyo University of Technology | Kobayashi T.,Tukuba Research Center | And 7 more authors.
Journal of Micromechanics and Microengineering | Year: 2013

In this paper, a piezoelectric cantilever with a Helmholtz resonator (HR) is proposed as a sound pressure sensor that generates a sufficiently large output voltage at a specific frequency without a power supply to drive the sensing element. A Pb (Zr, Ti) O3 (PZT) cantilever with dimensions of 1500 μm × 1000 μm × 2 μm is designed so that its mechanical resonance frequency agrees with the target frequency. When sound pressure is applied at the target frequency, a large piezoelectric voltage can be obtained due to a high amplification ratio. Additionally, the PZT cantilever is combined with a HR whose resonant frequency is designed to be equal to that of the cantilever. This multiplication of two resonant vibration systems can generate detectable signals by sound pressures of several Pascals. The fabricated sensor generated a piezoelectric voltage of 13.4 mV Pa-1 at the resonant frequency of 2.6 kHz. Furthermore, the fabricated sensor performed as an electrical trigger switch when a sound pressure of 2 Pa was applied at the resonant frequency. © 2013 IOP Publishing Ltd. Source


Tomimatsu Y.,Seiko Instruments Inc. | Tomimatsu Y.,Tukuba Research Center | Takahashi H.,Tokyo University of Technology | Kobayashi T.,Tukuba Research Center | And 7 more authors.
Journal of Micromechanics and Microengineering | Year: 2013

This paper describes a piezoelectric differential pressure sensor using a cantilevered structure with dimensions of 1500 × 1000 × 2 μm 3. A high degree of sensitivity is achieved without the power supply because only the base part of the cantilever is fixed and the piezoelectric material is used as a sensing element. The measurements indicate that the fabricated cantilever bends and a piezoelectric voltage was generated matching the piezoelectric theory for when a differential pressure is applied. The sensitivity to the applied differential pressure was 2.4 mV Pa-1 for a range between -30 Pa and 30 Pa. Additionally, it was also demonstrated that the sensor performs as a wake-up switch during the pressure shifts of 10 Pa with low-power consumption. © 2013 IOP Publishing Ltd. Source


Tomimatsu Y.,Tukuba Research Center | Tomimatsu Y.,Seiko Instruments Inc. | Takahashi H.,Tokyo University of Technology | Kuwana K.,Tokyo Denki University | And 8 more authors.
Mechatronics | Year: 2013

Power management is a fundamental issue in wireless sensor networks. In this paper, a piezoelectric flow sensor is proposed for use as a wake-up switch in a wireless sensor node to reduce power consumption. A cantilever with a Pb (Zr, Ti) O3 (PZT) thin film detects airflow changes surrounding the wireless sensor node. A prototype of the flow sensor is used to determine the relationship between the change in flow velocity and piezoelectric voltage of the cantilever. The fabricated sensor generates a piezoelectric voltage of several millivolts when the flow velocity changes at a rate of approximately 1 m/s. © 2013 Elsevier Ltd. All rights reserved. Source


Takahashi H.,Tokyo University of Technology | Tomimatsu Y.,Seiko Instruments Inc. | Tomimatsu Y.,Tukuba Research Center | Kobayashi T.,Tukuba Research Center | And 9 more authors.
Measurement Science and Technology | Year: 2014

This paper reports on a smart, intermittent driven particle sensor with an airflow trigger. A lead zirconate titanate cantilever functions as the trigger, which detects an airflow change without requiring a power supply to drive the sensing element. Because an airflow change indicates that the particle concentration has changed, the trigger switches the optical particle counter from sleep mode to active mode only when the particle concentration surrounding the sensor changes. The sensor power consumption in sleep mode is 100 times less than that in the active mode. Thus, this intermittent driven method significantly reduces the total power consumption of the particle sensor. In this paper, we fabricate a prototype of the particle sensor and demonstrate that the optical particle counter can be switched on by the fabricated trigger and thus that the particle concentration can be measured. © 2014 IOP Publishing Ltd. Source

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